Proximity detectors may be used to detect the presence or level of granular materials. In general, these proximity detectors must be, and remain, properly calibrated. There are a number of issues in the field that can make the calibration of a proximity detector problematic.
Proximity detectors come in a number of forms, e.g., optical, capacitive, etc. Each of these sensing mechanisms has its advantages and disadvantages. For example, capacitive sensors can be impacted by various environmental factors, such as humidity, which can alter the baseline capacitance reading in the absence of material in the proximity of the detector. As a second example, the strength of the signal from an optical sensor can be impacted by the color of the granular material. Light colored material (white/yellow) will allow more reflected light through while dark colored material (brown) gives a greater signal contrast between presence and absence of material. As a third example, various component pieces of the sensor (or associated electronics) can drift over time (e.g., diminished light output from an optical light source or diminished sensitivity for an optical detector). Thus, there is a need for a system implementing techniques to mitigate these issues.